This invention is a device for harvesting or lifting rooted plants that is readily adaptable for use with crops that are planted with variable row spacings. It is particularly suitable for lifting plants grown in rows in nursery beds when the plants are to be later transplanted. The device is especially well adapted for nursery use in lifting tree seedlings that will later be used for reforestation of unstocked lands.
Many food crops are first grown in nursery beds rather than planted directly. These are then removed from the beds and transplanted into fields or forest land where the crop matures. Among these plants might be mentioned many leaf vegetables and tomatoes as well as tree seedlings. It is important that the root structure of the plants is relatively undamaged when they are lifted from the nursery beds. Otherwise, the combined shock of transplanting and root loss will cause a major adverse effect on ultimate crop yield. The same situation also applies to coniferous trees to be used for reforestation. Tree seedlings are grown in extremely large nurseries in an open-field situation. In the United States alone, the annual requirements are literally hundreds of millions of seedlings. As is the case with vegetables, a major crop gain can be expected if the seedlings can be harvested with relatively intact root structures.
A number of harvesting devices are available for lifting row plants that are subsequently to be transplanted. Among these might be mentioned Arnold et al., U.S. Pat. Nos. 3,693,721; Mayo et al., 3,743,024; Storms, 3,964,550; and Puch, Sr, et al., 3,968,842. All of these lifters grip the plants a short distance above the ground line between pairs of opposed resilient belts. As the machine is moved down the row the plants are guided between the belts and literally pulled out of the ground. The the best pairs transport them to a receiving station.
While many crops are planted with standard row spacings, this is not always the case. In the United States it is fairly conventional for tree seedlings to be planted in beds containing eight rows spaced six inches apart. However, some seedlings are transplanted and allowed to grow in the nursery for an extra year in order to increase vigor. Transplanted seedlings are typically grown in six rows which are on eight-inch centers. To the present time, no single harvester has been available which can be adapted to lift both of these tree crops. The nursery has had to bear the considerable expense of buying separate harvesters to use on the different row spacings.